Array Combining Scatter Functions

Fortran 90 allows indirect addressing, however if,

    INTEGER, DIMENSION(4) :: A = 1, B = 2
    INTEGER, DIMENSION(3) :: W = (/1,2,2/)

then writing

 A(W) = A(W) + 2*B(1:3)

is incorrect due to the multiple assignments to A(2). We are able to use combining scatter functions:

 A = SUM_SCATTER(2*B(1:3),A,W)

now A equals (/5,9,1,1/). This performs

 A(1) = A(1) + 2*B(1)
 A(2) = A(2) + 2*B(2) + 2*B(3)

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